Data enabled mobile devices, such as smartphones, have become widely adopted, and applications and data requirements for such data enabled mobile devices have increased. As multimedia and data rich applications have become more prevalent, increased data throughput to and from a data enabled mobile device is needed. In response, newer wireless networks contemplate higher data throughput rates. For example, in a Long Term Evolution-Advanced (LTE-A) system, peak target data rates are 1 Gbps and 500 Mbps for downlink and uplink respectively. To achieve such target data rates, one potential approach is to use carrier aggregation techniques that utilize bandwidth aggregation of a variety of different arrangements of component carriers (CCs), including the same or different bandwidths, adjacent or non-adjacent CCs in the same frequency band or different frequency bands.
In the Third Generation Partnership Project (3GPP), Long Term Evolution-Advanced (LTE-A), carrier aggregation was introduced in Release 10. With carrier aggregation, multiple component carriers may be allocated for both downlink and/or uplink transmissions.
In addition, from Long-Term Evolution (LTE) Standard Release 8 onwards, a UE is typically required to perform radio measurements of neighbouring cells, for example for handover purposes, etc. During normal data communications, the UE is typically camped on a frequency and Radio Access Technology (RAT) of its serving cell. However, radio measurements are usually also performed on one or more different frequencies (inter-frequency) and/or different RATs (inter-RAT) than the frequency and/or RAT of its serving cell. Inter-frequency measurements are performed between the channels of different frequencies within the same or a different LTE band. Inter-RAT measurements are performed between the channels of different Radio Access Technologies (e.g. GSM, UMTS, LTE).
A UE having a single transceiver is typically unable to simultaneously receive/send data on one frequency and perform measurements on another frequency. Thus the UE switches to another frequency or frequency band to perform measurements. One way to address such measurements is by having a base station schedule “measurement gaps” (e.g. time slots) between the data communications of the UE with the network (see e.g. 3GPP TS 36.331 v8.18.0 “Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification (Release 8)”, December 2012, and 3GPP TS 36.306 v8.7.0 “Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio access capabilities (Release 8)”, June 2010, the contents of which are both incorporated herein by reference). During these gaps, a UE may switch to another frequency or RAT and perform measurements. Once the measurement gap has elapsed, data communications with the network may resume. In UMTS, a similar approach is referred to as “compressed mode”.